Effect of Geometric Confinement on the Stabilization of Skyrmions

TL;DR

This study investigates how geometric confinement influences skyrmion stability, revealing that surface DMI energy reduction enhances skyrmion stabilization at low magnetic fields, with implications for magnetic device design.

Contribution

The paper demonstrates that the geometric confinement effect on skyrmion stability arises from surface DMI energy reduction, providing a new understanding of skyrmion stabilization mechanisms.

Findings

Skyrmions are stabilized inside nano-domains due to geometric confinement.

Surface DMI energy is effectively reduced in confined geometries.

Zero surface DMI energy significantly enhances skyrmion stability at low fields.

Abstract

In this paper, we study the stability of skyrmions (SKYs) caused by the geometric confinement (GC) effect observed in nano-domains in recent experiments, where SKYs appear only inside the boundary and is stable at the low magnetic field region. However, the mechanism of the GC effect is unclear for skyrmions. We numerically find that this effect is not observed in the standard model, in which the Dzyaloshinskii-Moriya interaction (DMI) energy is discretized on lattice edges, while the effect is observed in a discrete model where the DMI energy is defined on lattice volume elements. In the latter model, the DMI energy on the surfaces effectively becomes very small compared with that of the inside. From this observation, we study a model with zero DMI energy on the surfaces parallel to the external magnetic field and find that SKY is significantly stabilized in the sample in the low magnetic field region.